1. Field of the Invention
This invention relates to a spacer which is used to set a distance between an adjustable stop member and a rotating gear in a power transmitting device. In particular, this invention relates to the use of a spacer which, when worn away, produces a running clearance between two parts in the power transmission device and the residue is non-deleterious to moving parts in a power transmitting device.
2. Description of the Prior Art
It has been well known in the automotive power transmission art that large diameter gears in power transmitting devices, such as differentials, deflect axially under load conditions. Typically, thrust screws or other stop members are used to limit the axial deflection of these large gears. Such a thrust screw is shown in U.S. Pat. No. 2,651,216 to H. W. Alden issued Sept. 8, 1953.
Normally, the thrust screw is axially spaced from the side of the large gear or ring gear to limit axial deflection when the differential is loaded. In order to keep stresses within acceptable levels, the distance between the thrust screw and the ring gear must be controlled accurately to insure that deflections are kept within allowable limits. In the past, the difference between the thrust screw and the ring gear has been set using feeler gauges or shim stock with a thickness of 0.010 to 0.020 inches. This has been found to be a very time consuming process and has caused problems in assembly line production.
The spacer of the present invention is bonded to the bottom of the thrust screw and abuts the ring gear. The spacer is made of a wearable material which is of a thickness equal to the 0.010 to 0.020 required running clearance. As the ring gear rotates, the spacer is worn away thus producing the required running clearance. The spacer, which is made of a material such as carbon, disintragates producing residue that is non deleterious to bearings or gearing.